Superior solid solubility of MnSiO3 in CaSiO3 perovskite
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The silicate perovskite phase relation between CaSiO3 and MnSiO3 was investigated at 35–52 GPa and at 1,800 K using laser-heated diamond anvil cells combined with angle-dispersive synchrotron X-ray diffraction and energy-dispersive X-ray spectroscopic chemical analyses with scanning or transmission electron microscopy. We found that MnSiO3 can be incorporated into CaSiO3 perovskite up to 55, and 20 mol % of CaSiO3 is soluble in MnSiO3 perovskite. The range of 55–80 mol % of MnSiO3 in the CaSiO3–MnSiO3 perovskite system could be immiscible. We also observed that the two perovskite structured phases of the Mn-bearing CaSiO3 and the Ca-bearing MnSiO3 coexisted at these conditions. The Mn-bearing CaSiO3 perovskite has non-cubic symmetry and the Ca-bearing MnSiO3 perovskite has an orthorhombic structure with space group Pbnm. All the perovskite structured phases in the CaSiO3–MnSiO3 system convert to the amorphous phase during pressure release. MnSiO3 is the first chemical component confirmed to show such a superior solid solubility in CaSiO3 perovskite.
KeywordsSolid solution MnSiO3 perovskite CaSiO3 perovskite High pressure High temperature
We thank T. Kikegawa and D. Hamane for their technical support with the X-ray diffraction experiments. We also thank Prof. M. Akaogi and an anonymous reviewer for helpful comments and constructive criticism. Synchrotron X-ray diffraction experiments were performed at the Photon Factory (proposal no. 2008G012, 2010G060, 2012G050). T. Nagai is partly supported by JSPS KAKENHI Grant Number 18340167 and MEXT KAKENHI Grant Number 20103002. S. Itoh is partly supported by MEXT KAKENHI Grant Number 20002002 and 22224010.
- Fujino K, Miyajima N, Yagi T, Kondo T, Funamori N (1998) Analytical electron microscopy of the Garnet-perovskite transformation in a laser-heated diamond anvil cell. In: Manghnani MH, Yagi T (eds) Properties of earth and planet mater at high press and temp, Geophys Monogr Ser, vol 101. AGU, Washington DC, pp 409–417Google Scholar
- Stixrude L, Cohen RE, Yu RC, Krakauer H (1996) Prediction of phase transition in CaSiO3 perovskite and implications for lower mantle structure. Am Miner 81:1293–1296Google Scholar